To attach a menu to the window.
winio@('%mn[menu_spec]', . . .)
Question mark (?) - All the strings are placed in order at the end of the format
description, one for each and every menu item that has a call-back function.
Grave accent (`) - Creates an enhanced menu (see
See Menu format.
If you want the percentage character % to appear in the text of a menu
item then you must put %% in the code.
%pm - Popup Menu, %sm - Modify System Menu